1. Field of the Invention
The present invention relates to audio power amplifiers and more particularly to audio power amplifiers having single-ended power supplies.
2. Description of the Relevant Art
A variety of audio power amplifiers are well known in the art. When an audio power amplifier is used in a system having a single-ended power supply, such as a power supply providing a positive voltage with respect to ground and no negative voltage, the amplifier is typically designed with a push-pull configured output stage including a large AC coupling capacitor connected at the output terminal of the amplifier. The large AC coupling capacitor is included to maintain the DC output level at zero volts. Since an input signal provided to the power amplifier is level shifted to an average voltage which is intermediate between the positive supply and ground to allow the signal to vary between the supply voltages, the AC coupling capacitor blocks the intermediate DC voltage at the push-pull output stage to thereby provide an output signal with a zero volt DC level.
A problem associated with such audio power amplifiers is a loud popping noise generated by the amplifier at turn-on and turn-off. The popping noise generated by the amplifier is the result of the quick charging and discharging of the large AC coupling capacitor at turn-on and turn-off. An audio power amplifier that is not associated with this popping characteristic is desirable.